What is hormone replacement therapy (HRT)?

Hormone replacement therapy is estrogen or combination estrogen/progestin medication, available only by prescription. It is generally prescribed to relieve menopausal symptoms.

Estrogen and progestin are usually given together because estrogens given alone increase the risk for endometrial cancer — the uncontrolled growth and spread of abnormal cells from the inner lining of the uterus. Prescribing progestin along with the estrogen, creating a balance, alleviates this effect. Estrogen is a female hormone that brings about changes in other organs in the body. It generally comes from animal sources. Progestin is a female hormone that prepares the uterus for a pregnancy each month.

These are available in oral formulations, injections, vaginal creams and transdermal (patch) forms. There are also formulations (pills and a patch) that combine estrogen/progestin into one dosage form.

What are the risks of HRT?

The U.S. National Institutes of Health stopped a 16,600-woman study of hormone replacement therapy in July 2002 — three years early — and advised other women who use the estrogen-progestin combination to ask their doctors if they should discontinue its use. The study was sponsored by the Women's Health Initiative. The study found that the overall risks of estrogen plus progestin outweighed the benefits. The researchers determined that long-term use of estrogen and progestin significantly increased the risk of breast cancer, heart disease, stroke, blood clots, and urinary incontinence.

At the time, six million American women were on the hormone combination, either for short-term relief of menopausal symptoms or to prevent heart disease and osteoporosis. The study concluded that long-term use of estrogen and progestin increased a woman's risk of a stroke by 41 per cent, of a heart attack by 29 per cent, and of breast cancer by 24 per cent.

The combination did, however, cut the risk of colon cancer and hip fractures by one-third.

The results mean that in one year, for every 10,000 women who take the estrogen-progestin combination, there will be eight more breast cancers, eight more strokes and seven more heart attacks, as well as six fewer colon cancers and five fewer hip fractures — compared with 10,000 women who didn't take the hormones.

HRT also increases the breast density of many women, making breast abnormalities harder to detect in mammograms.

The study shows visible short-term risks of heart disease, with the cardiovascular risk actually jumping within the first year of HRT use. The cancer risk didn't appear until around the fourth year, suggesting a long-term risk posed by HRT.

Some women report side-effects from taking HRT, including unusual vaginal discharge and bleeding, headaches, nausea, fluid retention and swollen breasts.

The NIH stopped a second study in February 2004. That study included women who had had hysterectomies and took only estrogen. Researchers determined that estrogen alone increased the risk of stroke and blood clots. Use of estrogen alone decreased the risk of breast cancer compared to women who were given a placebo. There was no change in the risk of colorectal cancer. But — like the study on women using the estrogen-progestin combination — women using estrogen alone had an increased risk of urinary incontinence and a decreased risk of hip fractures.

The 16,600 women who participated in the first study, published in July 2002 in the Journal of the American Medical Association, were taking Prempro (called Premplus in Canada) for at least five years.

According to the Kaiser Family Foundation, a non-profit research group, 46 million prescriptions worth $1 billion were written for Premarin, a hormone replacement drug, in 2000, making it the second-most-prescribed drug in the U.S. after cholesterol-lowering Lipitor, made by Pfizer Inc.

But on May 20, 2008, a report was released to the World Congress on the Menopause that suggests that HRT is safe for healthy women who are entering menopause. The report came out of the First Global Summit on Menopause-Related Issues, which was held in Zurich on March 29 and 30, 2008.

Forty menopause experts met to review public perceptions, along with the risks and benefits of HRT. They concluded that that Women's Health Initiative study was not completely representative of women taking HRT and included a larger than usual number of people with higher risk factors. One issue raised was that the average age of study participants was 63, and that is 10 years older than the age most women begin taking HRT. Other issues that arose were that 36 per cent of the women in the study had high blood pressure, 49 per cent were current or former smokers and 34 per cent were obese.

The Zurich Summit concluded that the combined estrogen and progesterone treatment:

• Does not increase the risk of chronic heart disease in healthy women ages 50-59.
• Can lead to a slightly increased risk of breast cancer - although the risk is minimal compared to other risk factors.
• Is effective in maintaining bone health in 50 to 59-year-old postmenopausal women.
• Does not impair mental processes in healthy women ages 50-59, and may even delay the decrease of cognitive functions in this group.

The experts recommended that women should decide whether HRT is appropriate for them only after consulting their doctor.

Canada's guidelines

On Feb. 7, 2006, the Society of Obstetricians and Gynecologists of Canada issued new guidelines on the use of combined HRT for post-menopausal women. The new guidelines were designed to quell fears and respond to the controversy arising from the studies sponsored by the Women's Health Initiative.

The SOGC advised that combined HRT continues to be the best option to treat moderate to severe menopausal symptoms, including hot flashes, night sweats and mood changes. The drugs should be prescribed at the lowest effective dosage for "the appropriate duration," the guidelines said.

The agency further said that extended periods of HRT should only be prescribed after "proper counselling about the benefits and risks." It also recommended periodic evaluations of treatment.

The society urged doctors not to prescribe HRT solely to prevent heart disease or dementia.

The SOGC concluded that HRT remains the most effective treatment for symptoms of menopause and should be used under the following three conditions:

• If a woman is experiencing early menopause (before age 45).
• If hot flashes interfere with sleep.
• For the treatment of osteoporosis, especially in women with hot flashes.

What are the alternatives to HRT?

Regular exercise, coupled with 1,500 mg of calcium and 400 IU of vitamin D per day, is one proposed treatment to decrease the bone loss associated with osteoporosis.

Regular exercise, good diet and non-smoking will help prevent heart disease and is recommended for all patients, regardless of the use of HRT. Non-hormonal therapies are available to reduce the symptoms of menopause, varying from the use of soy products, lubricants and vitamin supplements, to prescription medications that stabilize the nervous system.

* This site is intended for information purposes only. It's not intended to be a substitute for consultation with a physician.